Does Not-for-Profit Own Teachers' Courses?

We are a not for profit that has several courses and workshops developed by teachers who are contractors. We want to publish the courseware online. What is required to be clear that the IP is owned by our organization not the teacher? They were paid for developing the materials. Absent an agreement to the contrary, a contractor acquires copyright in works created for someone else. (Check our previous entry, Who Owns What I Write For NonProfit?) So if your non-profit wants to reproduce copyrighted materials, you'll need to have an agreement in place. You may have already signed such an agreement, or you can go back now and seek either an assignment or a license, both discussed below.
Acquiring ownership of contractor works. Your non-profit will own the copyright in the coursework (and not have to seek permission) if the contractor signed a work for hire agreement at the time the materials were prepared. Alternatively, you and the contractor might have signed an agreement containing an assignment provision -- an arrangement that says something to the effect of, "I assign all copyright in the work I created to the not-for-profit." Either of these arrangements allow the non-profit, as copyright owner, to freely exploit the materials including publish them online. Although it is probably too late to execute a work made for hire --  such agreements should be made in anticipation of the completed work -- the contractor can execute an assignment at any time.
License it. Even if the non-profit doesn't own copyright and can't acquire ownership via an assignment,  the nonprofit may have acquired a nonexclusive implied license to reproduce the materials for their intended purpose. That is, if you hired the teachers to create course materials and the teachers were aware of your intention to publish the materials online, you would still have an implied license to publish the materials online. The drawback to an implied license is that it is nonexclusive and the teacher can offer the course materials to others, as well. In that case, you can still achieve your goal by executing an exclusive license for the rights you want. You can find sample agreement for most of the purposes discussed above in our Getting Permission book.